1. Technical Field
The present invention relates to a sample analysis element, a detecting device, and the like that are provided with a metallic nano-body such as a metallic nanoparticle or a metallic nano-projection.
2. Related Art
A sample analysis element using localized surface plasmon resonance (LSPR) is known. Such a sample analysis element is provided with metallic nano-bodies, that is, metallic nanoparticles which are dispersed on, for example, a dielectric surface. The metallic nanoparticle is formed sufficiently smaller than the wavelength of excitation light, for example. If the metallic nanoparticle is irradiated with the excitation light, all electric dipoles are aligned, and thus an enhanced electric field is induced. As a result, near-field light is generated on the surface of the metallic nanoparticle. A so-called hot spot is formed.
In Yizhuo Chu et al, “Experimental study of the interaction between localized and propagating surface plasmons”, OPTICS LETTERS, U.S.A. Feb. 1, 2009, Vol. 34, No. 3, p. 244-246, the metallic nanoparticles are disposed in a lattice form at a predetermined pitch. If the size of the pitch is set to be a specific numerical value, propagating surface plasmon resonance (PSPR) based on an evanescent wave occurs. The propagating surface plasmon resonance is combined with the localized surface plasmon resonance. A so-called hybrid mode is established. In this way, the localized surface plasmon resonance is enhanced by the propagating surface plasmon resonance, and thus the near-field light is intensified on the surface of the metallic nanoparticle.
The sample analysis element described above can be used in a target substance detection device. As disclosed in Yizhuo Chu et al, “Experimental study of the interaction between localized and propagating surface plasmons”, OPTICS LETTERS, U.S.A. Feb. 1, 2009, Vol. 34, No. 3, p. 244-246, if the pitch is set to be the wavelength of the evanescent wave that causes the propagating surface plasmon resonance, the surface density of the hot spot is significantly reduced on the dielectric surface, and thus the target substance cannot be easily stuck to the hot spot.